aeon

noun

• 1 (often aeons) an indefinite and very long period of time:he reached the crag aeons before I arrived
• Astronomy & Geology a unit of time equal to a thousand million years.
• Geology a major division of geological time, subdivided into eras:the Precambrian aeon

• 2 Philosophy (in Neoplatonism, Platonism, and Gnosticism) a power existing from eternity; an emanation or phase of the supreme deity.